The present invention relates in general to reaching and recovering the natural heat found in rock deep within the earth, more specifically to laser drilling a dry hole under a vacuum and using the heat with a closed circulating heat recovery system, to produce geothermal electricity.
Geothermal energy is the earths most plentiful renewable resource and has not fully reached its potential. The heat deep within the earth has been known of for many centuries, this heat has been displayed as volcanos, geysers, and even hot springs. In some geothermal locations found around the earth, pools of super hot water have been trapped beneath a cap, or a layer of impermeable rock these areas are known as wet geothermal zones. This is where geothermal energy has it""s infancy. Wells have been successfully drilled into these pools. The heated water has been used in various ways to generate mechanical power, then harnessed to generate electricity. However the industry is still struggling with problems, such as the minerals and salts carried in the water, causing maintenance difficulties. The depletion of the well pressure and replenishing the reservoir have been problems. Also the geothermal industry has been limited to the wet geothermal zones, which are not always near the metropolitan areas where electric power is needed. This has left the dry geothermal zones virtually untapped.
The present invention is well suited to take geothermal energy to the next level, by utilizing old and well known technologies, with a few new apparatuses to circumvent the barriers of drilling an ultra deep hole into the dry geothermal zone, found everywhere beneath the surface of the earth.
Heretofore, drilling a bore-hole into the earth is a well known art, and accomplished in several ways, all having limitations to drilling an ultra deep hole. The most common method of drilling is used in the search of oil and gas, this method uses a drilling fluid or mud, the mud is pumped down the drill pipe to flush the drill cuttings from the hole. This mud or fluid could not withstand the temperatures of an ultra deep hole. U.S. Pat. No. 5,837,654 to Carroll et al, shows a high temperature drilling fluid, that would also fall short of the temperatures expected. Other setbacks include the weight of a fluid column this tall would be difficult to pump, even the added weight of conventional drill pipe may cause problems, also the time it takes to periodically pull the drill string to replace the rotary drill bit is a setback.
Lasers have been used for drilling, one has a plurality of lasers focused to bore horizontally, U.S. Pat. No. 3,693,718 to Stout. U.S. Pat. No. 3,871,485 to Keenan Jr, shows a generator and laser mounted within the drill string, with mud or drilling fluid driving a turbine to power it. U.S. Pat. No. 3,977,478 to Shuck, shows a sealed hole that has been pressurized for laser drilling, however even more pressure is required as the hole deepens, setting limitations.
A vacuum is utilized in the present invention, used to remove vapors, ash and gases from the hole, also to create a sub-atmospheric condition within the hole this air flow will also keep smoke and vapors away from the reflecting surfaces. Many devices have been used to achieve a vacuum, such as these U.S. Pat. No. 5,069,582 to Young, U.S. Pat. No. 4,745,655 to Johnson, and U.S. Pat. No. 5,768,743 to Webster, all of these use a positive air flow, have chambers and air ducts, some use compressed air and one uses a fan. All of these vacuum producing devices lack the power needed for the task at hand.
For heat recovery from geothermal wells, wet or dry, many systems have been developed but insofar as the applicant is aware, none of these incorporate a closed double D pipe circulation system.
Accordingly the objects and advantages of the present invention are.
a. To provide a down hole environment suitable for the effective use of a laser beam, with a vacuum strong enough to maintain a sub-atmospheric pressure while allowing a constant air flow to remove the smoke, vapors and ash caused by laser drilling.
b. To drill with a significantly lighter drill pipe than conventional drill pipe, allowing a deeper hole.
c. To accomplish deep hole drilling without the need to pull the drill string to replace worn drill bits.
d. To operate a laser reflecting device at the bottom of a drill string remotely, with no mechanical device extending from the surface.
e. To eliminate the use of geothermal water and brine, with their corrosive effects to current geothermal systems.
f. To provide a more efficient heat transfer system from dry geothermal zones.
g. To provide the means to locate geothermal power plants almost anywhere.
h. The main objective of the present invention is to provide the means to produce endless inexpensive electricity, using no fuels and having no pollution or waste products to dispose of, thus improving the environment and conserving natural resources.